Water soluble lubricant

ABSTRACT

A WATER SOLUBLE COMPOSITION COMPRISING THE PRODUCT OBTAINED BY TRANSESTERIFYING A TRIGLYCERIDE (E.G. CASTOR OIL) WITH A POLYMERIC ALKYLENE OXIDE GLYCOL UNTIL THE REACTION PRODUCTS ARE WATER-SOLUBLE AND THEN ESTERIFYING THE HYDROXY COMPOUNDS PRESENT WITH A CARBOXYLIC OR DICARBOXYLIC ACID. THESE PRODUCTS ARE OF VALUE AS LUBRICANTS IN A WIDE VARIETY OF FIELDS.

United States Patent m 3,634,245 WATER SOLUBLE LUBRICANT Inara DagnijaMeisters, Homewood. lit, assignor to Kerns United Corporation NoDrawing. Filed June 18, 1969, Ser. No. 834,556 Int. Cl. Cltlm ]/26 US.Cl. 252-493 8 Claims ABSTRACT OF THE DISCLOSURE A water solublecomposition comprising the product obtained by transesterifying atriglyceride (e.g. castor oil) with a polymeric alkylene oxide glycoluntil the reaction products are water-soluble and then esterifying thehydroxy compounds present with a carboxylic or dicarboxylic acid. Theseproducts are of value as lubricants in a wide variety of fields.

Metal working lubrication has been accomplished, as is well known, bythe use of mineral and/ or fatty oils. In the early technology, thesefats and oils were used alone, but with the advent of improvedtechnology, it was useful to prepare aqueous emulsions of mineral and/orfatty oils in order to reduce costs, improve cooling capacity, and givegenerally better performance. Until recent years almost all watercontaining lubricants were emulsions of fatty and/or mineral oils whichmight or might not contain various additives for particularapplications. However, emulsion type products have several inherentproblems, as, for example, emulsion stability, and for this reason andothers they often find their utility limited. In recent years, watercontaining lubricants of the solution type have become available and inareas where cooling ability is the primary consideration the watersoluble lubricant has shown great merit. However, where conditionsrequire both a high degree of cooling plus a high degree of hydrodynamicor oil film lubricity characteristics, the water soluble lubricants havenot been suitable because they have been unable to deposit a filmcontaining sufficient lubricity for proper function under hydrodynamicconditions.

The water soluble lubricants appear to function by plating out thelubricant onto the surface to be lubricated during use. This appears tooccur because heat of friction raises the temperature of the solutionabove its cloud point and causes the solution to change to a dispersionor emulsion, whereby the plating out phenomena occurs. In the past,however, the lubricating benefit derived from the film of plate out ofthese aqueous solution lubricants has been well below the degree oflubricity provided by the conventionally emulsified materials.

This invention now provides an improved water soluble lubricant whichdeposits a film on surfaces to be lubricated where the deposited filmhas greatly improved lubrication and anti-frictional qualities.

In one embodiment of the invention there is provided a water solubleproduct obtained by transesterifying a triglyceride such as castor oilor similar triglyceride with a polyoxyalkylene polyol until the reactionproducts are water soluble and then esterifying the hydroxy compoundspresent with a carboxylic or dicarboxylic acid.

Another embodiment of the invention involves an aqueous solutionformulation useful as a metal working lubricant. Still anotherembodiment of the invention is the process for lubricating metal byproviding on its surface a lubricating film of the water solublelubricant composition above defined.

In making the compositions of the invention, a first step 3,634,245Patented Jan. ll, 1972 requires the transesterification of thetriglyceride, pref erably castor oil, with a polyoxyalkylenepolyolhaving a molecular weight of at least about 1000 until the reactionproducts are water soluble. As is well known, castor oil is atriglyceride which is predominantly the ricinoleic acid ester ofglycerol, but which contains minor amounts of the oleic and linoleicesters. Thus, in the transesterification step, the polyoxyalkylenepolyol will replace some or all of the glycerol OH groups and generateOH groups from the glycerol. The free OH groups in this water solubleproduct are then reacted with a carboxylic acid or a dicarboxylic acidto prepare the product which is subsequently formulated for use as willbe discussed below.

In the transesterification procedure, the preferred amount ofpolyoxyalkylene polyol used will be on an approximate 1:1 moleequivalent weight ratio with the triglyceride. At higher content ofpolyoxyalkylene polyol there will be a decrease in the lubricity valueafforded by the end product. At significantly lower content ofpolyoxyalkylene polyol, water solubility will not be achieved. Theeffective range for water solubility and good lubricity is 0.75 to 2.0mole equivalents of the polyoxyalkylene polyol to 1.0 mole equivalent ofthe triglyceride.

In carrying out this transesterification step, it is preferred to removeair from the reaction medium and this is done preferably by sweepingnitrogen through the reaction equipment. The temperature of thetransesterification process is on the order of 400 to 450 F. and thetime of reaction will, of course, vary with reaction kettle size andother factors, but, in general, will be from about 10 to 20 hours.Completion of the reaction is determined when 5 g. of the product iscompletely soluble in ml. of water at 100 F. The polyoxyalkylene polyolused in the reaction may be any one of a large number of such productswhich are commercially available, but for use in this invention, theglycol used will have a molecular weight of at least about 1000. Ifglycols of molecular weight less than this are used, the products arenot water soluble and not useful in this invention. As a simple exampleof such materials that may be used reference is made to polyethyleneglycol. Other polyoxyalkylenepolyols may be used such as the watersoluble high molecular weight viscous liquid polyalkylene polyols whichcontain ethylene oxide and/or propylene oxide groups available asPluracol V5 and V7 manufactured by Wyandotte Chemicals Corporation orthe polyalkylene glycols known as Ucons available from Union CarbideChemicals Company.

The transesterification is carried out generally in the presence of acatalyst. The catalyst used is an important factor in achieving watersolubility of the transesterification reaction product. Buffer catalystssuch as alkali metal carbonates and acetates, (eg sodium carbonate,sodium acetate, and the like) are necessary. Acidic and basic catalystsproduce a product with only partial Water solubility.

When the transesterification reaction is complated as indicated by theabove water solubility test, reaction of the first product is made tooccur with the carboxylic or dicarboxylic acid and such acids may be anyof the wellknown long-chain fatty acids such as lauric, oleic, stearicacid, ricinoleic, linoleic and the like. Dicarboxylic acids which may beused are succinic, adipic, glutaric, azelaic, and sebacic. Also usefulare aryl substituted fatty acids such as phenylstearic and the like.

In this second reaction step, a catalyst is also preferably used andp-toluenesulfonic acid or similar acidic catalyst (e.g.dodecylbenzenesulfonic acid, etc.) is employed. The temperature of thereaction may be from about 350 F. to 450 F. and reaction is continued bystirring the reactants at this temperature until completion of thereaction which is indicated by the acid number falling below to six.

The resulting product obtained by the above procedure is a viscous,amber fluid, soluble in 100 F. water with distinct cloud points below180 F. and gives a pH in a water solution of 7.0 to 7.7. This product isused by dilution with water and this formulation may also contain otheradditives as e.g. agents for rust protection, silicone polymers asdefoamers, chlorinated phenol type bactericides and the like. Generally,the formulation of product in water will be such that the amount oflubricant will be on the order of 5% to 50% by weight and preferably toIn order to further illustrate the invention the following examples aregiven:

EXAMPLE 1 A stainless steel reaction vessel is charged with 20 pounds ofcastor oil, 44.5 pounds of polyalkylene polyol containing ethylene oxideand propylene oxide groups and having a molecular weight of about 3000(Pluraeol V-5) and 0.15 pound of sodium acetate. The reaction vessel isswept with nitrogen at a rate of 5 to 10 cubic feet per hour and as themixture is agitated the temperature is raised to 425 F. After 17 hoursat this temperature a sample is taken and 5% by weight solution of theproduct in water at 100 F. is readily obtained. The temperature of thereaction mixture is then reduced to 375 F. and 5.5 pounds ofphenylstearic acid (Armour Neofat LPS) and 0.18 pound of p-toluenesulfonic acid is added. The temperature is raised to 420 F. and afterthe acid number reaches 3.8 (about 24 hours) the heat is removed andwhen the temperature drops to about 200 F. the reaction mixture isdischarged into containers for storage and subsequent use. The productis an amber fluid that has the following typical properties:

Acid number: 4.0 Hydroxyl number: 62 Saponification number: 68 Color[FAC]: 7 Flash point [COC]: 565 F. Fire point [COC]: 615 F. Specificgravity: 1.04 at 60/60 F. Viscosity at 100 F.: 2725 SUS Viscosity at 210F.: 410 SUS Viscosity index: 132

' EXAMPLE 2 A stainless steel reactor is charged with 21.1 pounds ofcastor oil and 45.3 pounds of Pluracol V-5 and 0.17 pound of sodiumacetate. Nitrogen is swept through the reaction kettle at 5 to 10 cubicfeet per hour and the temperature of the reactants is raised to 400 to450 F. while maintaining agitation. This temperature is held forapproximately 17 hours at which time a 5% by weight solution of theproduct in water at 100 F. is obtained as a clear solution. At thispoint the temperature of the reaction product is lowered to 380 F. and3.3 pounds of monosodium azelate and 0.07 pound of dodecyl benzenesulfonic acid are added. The reaction mass is maintained at 380 to 420F. with a nitrogen sweep being maintained for approximately 20 hoursafter which time an acid number of 3.5 is reached. The product is anamber fluid that has the following typical properties:

Acid number: 3.8 Hydroxyl number: 61.5 Saponifieation number: 71.2 Color[FA C]: 20 Flash point [COC]: 560 F. Fire point [COC]: 610 F. Specificgravity: 1.04 at 60/60 F. Viscosity at 100 F.: 3067 SUS Viscosity at 210F.: 436 SUS Viscosity index: 129

EXAMPLE 3 Example 1 is repeated except that the phenylstearie acid isreplaced with stearic acid and the product obtained has the followingproperties:

Acid number: 3.21

Hydroxyl number: 61 Saponification number: 69.3

Color [FAQ]: 2

Flash point [COC]: 625 F.

Fire point [COC]: 640 F. Specific gravity: 1.03 at /60 F. Viscosity at100 F.: 3059 SUS Viscosity at 210 F.: 464 SUS Viscosity index: 130

EXAMPLE 4 Example 1 is repeated except that the Pluracol V5 is replacedwith 47.2 pounds of polyethylene glycol of 2500 molecular weight (UconH1400). The fluid product obtained from this reaction has the followingtypical properties:

Acid number: 4.2

Hydroxyl number: 63

Saponification number: 57.6

Color [PAC]: 3

Flash point [COC]: 525 F.

Fire point [COC]: 620 F.

Specific gravity: 1.04 at 60/60 F. Viscosity at F.: 1687 SUS Viscosityat 210 F.: 252 SUS Viscosity index: 133

As indicated, the above compositions are used primarily as lubricants inthe metal working field. For this purpose the products are formulatedwith water and such formulations will contain from about 5 to about 50%by weight of the active lubricant. The following example illustrates thetype of lubricant formulations which may be employed.

EXAMPLE 5 The lubricant composition of Example 1 is formulated for saleas a concentrate as follows:

Parts by weight Water 74.58

Antirust agent 0.30 Tri sodium salt of ethylenediaminetetra acetic acid0 10 Sodium salt of pentachlorophenol 0.02 Product of Example 1 25 Theabove formulation is very effective as a mold release agent in the diecasting of aluminum.

In carrying out the mold release use for the product, a solution of 40parts of water to 1 part of the above formulation was applied to the dieby hand spray prior to closing the die and then injection ofapproximately 2 pounds of molten aluminum at 1200 F. was made. Castingtime was six seconds with an approximate pre-injection die temperatureof 450 F. The part cast was the body of a saber saw. When the die wasopen no sticking of the part to the die was experienced and the qualityof the surface of the cast part was considered good. In a comparativetest where the mold release agent was composed of a higher costcolloidal graphite in water, the graphite product gave good mold releaseat comparable dilution, but resulted in poorer surface of the cast part.

The products of the invention are also useful in the cold reduction ofsteel where the lubricant formulation is used at dilutions of about 8 toabout 25 parts of water to one part of the formulated product. Likewise,in the hot reduction of steel, the lubricant may be used as an additiveto the cooling Water used on the mill at a concentration of from 0.01%to 0.5% or may be applied to the rolls in the mill from a separatesystem at a concentration in water of from 1% to 20% parts by weight.

In chip forming metal working, the formulations of the invention will beused as concentrations in water of from 1% to 20% of various cutting andgrinding operations of ferrous and non-ferrous metals. Likewise, in wiredrawing of ferrous and non-ferrous metals, the lubricant is useful atconcentrations in the water of to 15% to draw copper, steel, and coppercoated steel wire. In metal deformation processes, the formulations maybe used as concentrations of from to 100% in water for lubrication ofthe deep drawing of metal. The lubricants are also useful in hot workingand other procedures well known in the trade.

The compositions of the invention generally provide excellent cooling,and excellent uniform lubrication, resulting in a more uniform surfaceof the work metal, easier cleaning of the residual film of lubricant anda greater economy owing to the longer life of the lubricant solution dueto the greater immunity to change of the operating parameters. By usingthe lubricants of the invention, good tool life, good finish on themachine part, and good lubrication in moving parts is generallyachieved. The lubricant of the invention has excellent ability todeposit a film on a hot surface making it a particularly good lubricantfor hot working of metals such as forging, hot rolling, and die casting.

The lubricants of the invention are also of value as a rubber partingagent in extrusion of crude rubber and steam curing, and are able toreplace the conventional soap/ silicone polymer mixtures usedheretofore. In order to further illustrate the characteristics of thelubricants of the invention, the following test results are given in thetable which follows:

hydroxy compounds present with phenylstearic acid until the acid numberof the product is below Six.

3. A lubricant formulation comprising an aqueous lubricating solutioncontaining at least about 50% by weight of water and from about 5 to 50%by weight of a water soluble lubricant composition obtained bytransesterifying at a temperature of from about 400 to 450 F. and in thepresence of a buffer catalyst 1 mole of castor oil with 1 mole ofpolyoxyalkylene polyol having a molecular weight of at least about 1000until the reaction products are water soluble and then esterifying thehydroxy compounds present with monosodium azelate until the acid numberof the product is below six.

4. A lubricant formulation comprising an aqueous solution containing atleast about 50% by weight of water and from about 5 to 50% by weight ofa water soluble lubricant composition obtained by transesterifying at atemperature of from about 400 to 450 F. and in the presence of a sodiumacetate catalyst, 1 mole of castor oil with 1 mole of a polyethyleneoxy,polypropylene oxy polyol of molecular weight of about 3000 until thereaction products are water soluble and then esterifying the hydroxycompounds present with stearic acid until the acid number of the productis below six.

5. A process for lubricating a metal surface in friction generatingcontact with another surface which comprises applying to the metalsurface a lubricating film of the composition of claim 1.

6. A process for lubricating a metal surface in friction generatingcontact with another surface which comprises TABLE-TEST CHARACTERISTICSOF 2% BY WEIGHT AQUEOUS SOLUTION OF LUBRICANTS AT 100 130 F.

Product tested Example (A) Commercial (B) Commercial (0) Soluble rollingoil drawing 011 cutting 011 1 2 3 4 Timk maximum 10 min. ass

load 3 8 8 12 20 10 20 20 Amsler oef. of fri tlon steel on steel 24 140).045 .047 .040 .031 .039 .046 .041 F l x t u at a 500 115 18a 10.0 11. 012. 0 9. 0 7. 0 8. 0 10. 0 1000 lb. 102. l4. 5 16. 5 20. 0 17. 0 16. 018. 0 20. 0 2000 lb. load 30. 0 30. O 35. 0 27. 0 19. 0 28. 0 31. 030001b. load 35. 0 37. 0 43. 0 38.0 28. 5 38. 0 40. 0 4000 lb. 10a 39. 546. 0 Fail 46. 0 42. 5 35. 0 45.0 4500 lb. 102. 45.0 52.0 46. 0 42. 038.0 46. 0

1 90% beef tallow; 8% tallow fatty acids; 2% emulsifier. 50% 200 5.11.5.at

100 F. mineral oil; lard oil; 5% oleic acid; 5% emulsifier 3 10%chlorinated paraffin 40%; 10% lard oil; 65% 200 S.U.S. at 100 F. mineraloil; 15% sodium sulfonate.

I claim:

1. A lubricant formulation comprising an aqueous lubricating solutioncontaining at least about by weight of water and from about 5 to 50% byweight of a water soluble lubricant composition obtained bytransesterifying at a temperature of from about 400 to 450 F. and in thepresence of a buffer catalyst 1 mole of castor oil with from 0.75 to 2.0moles of polyoxyalkylene polyol having a molecular weight of at leastabout 1000 until the reaction products are water soluble and thenesterifying the hydroxy compounds present with a member of the groupconsisting of high molecular weight fatty acids, phenyl substitutedfatty acids and aliphatic dicarboxylic acids until the acid number ofthe product is below six.

2. A lubricant formulation comprising an aqueous lubricating solutioncontaining at least about 50% by weight of water and from about 5 to 50%by weight of a water soluble lubricant composition obtained bytransesterifying at a temperature of from about 400 to 450 F. and in thepresence of a buifer catalyst 1 mole of castor oil with 1 mole ofpolyoxyalkylene polyol having a molecular weight of at least about 1000until the reaction products are water soluble and then esterifying theReferences Cited UNITED STATES PATENTS 2,925,429 2/ 1960 Kirkpatrick eta1. 260-4048 2,971,923 2/l961 Walker et al 252342 3,202,607 8/ 1965 Koch25256 R FOREIGN PATENTS 820,571 9/ 1959 Great Britain.

DANIEL E. WYMAN, Primary Examiner W. H. CANNON, Assistant ExaminerU.S.Cl.X.R.

